Just a quick step by step on how to get you Subscription ID from the New Azure Portal.
1) Browse to https://portal.azure.com and Sign into your account.
2) Once you are in the portal you should see the side panel with a tab for ‘Subscriptions’. Click on this to get to the next section. If the tab is not visible, then click on the ‘More services’ tab to find it.
3) In the new open panel you will see all the subscriptions you have access to and in the ‘Subscription ID’ column is the what you are looking for.